JPH0997401A - Impact detecting circuit for data recording and reproducing device, data recording and reproducing device provided with the impact detecting circuit, and method for setting sensitivity of filter applied to the impact detecting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect an impact even if the intensity of the impact is small, insofar as the frequency of the impact is a frequency near a resonance point by setting detection sensitivity at an impact detecting circuit taking the resonance point of the device into consideration. SOLUTION: The impact detecting circuit 24 for data recording and reproducing device has an impact sensor 241 which detects the impact applied on the data recording and reproducing device and outputs the signal according to the intensity of the impact, an amplifier 242 which amplifies the output signal from this sensor, a filter 243 which is so composed as to cut the high-frequency component of the output of the amplifier and is set in the sensitivity in the frequency region near the resonance point of the device higher than the sensitivity in another frequency region and a comparator 244 which is a binarization circuit for binarizing the output of this filter at a specified level. The output of the comparator 244 is used as an inhibition signal for a writing operation. The detected sensitivity of the impact detecting circuit 24 taking the resonance point of the device into consideration is set in such a manner, by which the impact applied on the device is surely detected, insofar as the frequency thereof is the frequency near the resonance point even if the intensity of the impact is small.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a shock applied to a data recording / reproducing apparatus for recording / reproducing data by a head, thereby erroneously moving adjacent heads due to movement of the head due to the shock. The present invention relates to a shock detecting circuit for a data recording / reproducing apparatus suitable for preventing writing, a data recording / reproducing apparatus having the same shock detecting circuit, and a sensitivity setting method of a filter applied to the shock detecting circuit.

[0002]

2. Description of the Related Art In a data recording / reproducing apparatus for recording / reproducing data by a head, the relationship between the head and the layout (arrangement) of tracks is generally as shown in FIG. Further, as shown in FIG. 2A, servo data areas (servo areas) used for positioning control and the like are arranged at equal intervals on the track.

The position of the head is detected by the information (servo data) read from the servo area. If this position deviates from a predetermined position, the data recording / reproducing apparatus is set not to perform the write operation.
The displacement of the head is likely to occur when a shock is applied to the data recording / reproducing device. That is, the track pitch T
In contrast to the conditions of p, track width Tw, and servo area interval (servo data interval) Is, the condition of Vm * Is> Tp-Tw is satisfied between the moving speed Vm of the head when an impact is applied. , There is a possibility that the adjacent track (track1 in the example of FIG. 8) is erroneously written to erase the data of the adjacent track.

To prevent this, the interval Is of the servo area may be shortened or the track width Tw may be reduced. Here, as a method for shortening the interval Is of the servo areas, two methods are known: a method of increasing the number of rotations of the disk and a method of increasing the number of servo areas.

However, when the number of rotations is increased, the data writing frequency becomes higher. Further, when the number of servo areas is increased, there is a problem that the efficiency per surface (disk surface) is lowered. Therefore, the number of servo areas cannot be easily increased.

On the other hand, reducing Tw means that S of the signal is
There is a problem that an error is likely to occur because the N ratio is deteriorated. For this reason, conventionally, in consideration of the displacement of the head when a shock is applied to the data recording / reproducing apparatus, when the displacement of a certain amount or more is detected, the writing is stopped. However, since the positional deviation is detected based on the servo data, there is a time delay in detecting the positional deviation. For this reason, if the shock frequency is high, it is possible to detect the position shift of the head based on the servo data and move the head to write to the adjacent track and erase the data of the adjacent track before stopping writing. There is a nature.

Therefore, in recent years, a shock detection circuit for detecting that a shock has been applied to the data recording / reproducing apparatus is provided,
A method for stopping the write operation according to the detection output of the impact detection circuit has come to be applied.

Usually, the shock detection circuit detects a shock received and outputs a signal according to the strength of the shock (shock sensor), an amplifier for amplifying the output of the sensor, and a resonance point of the sensor. In order to avoid a malfunction in the amplifier, it is composed of a low-pass filter (LPF) that cuts the high frequency component of the output of the amplifier (the sensor amplified by it) and a comparator that compares the output of this filter with the reference detection level. . However, the impact detection circuit having such a configuration cannot sufficiently prevent the data destruction of the adjacent track when the impact occurs during the write operation.

[0009]

As described above, a recent data recording / reproducing apparatus represented by a magnetic disk apparatus is composed of a shock sensor, a low pass filter (LPF), etc. for detecting a shock applied to the apparatus. The impact detection circuit is provided, and the write operation is stopped according to the impact detection output from the impact detection circuit to prevent accidental writing to an adjacent track.

However, in such a conventional shock detecting circuit, even if a shock is applied to the device, the shock may not be detected and the data may be written, so that the data destruction of the adjacent track is sufficiently prevented. There was a problem that I could not do it.

Then, as a result of the inventors' investigation of this factor,
It has been recognized that the actual movement amount of the head depends on the frequency of the shock, and depending on the frequency, the head may be moved even with a small shock. Therefore, when a shock of such a frequency is applied, the track density of 600 TPI is particularly high in the conventional method of only detecting the shock at a constant detection level with respect to the frequency.
In a region exceeding (track / inch), reliable impact detection cannot be performed, and data destruction of adjacent tracks cannot be sufficiently prevented.

The present invention has been made in consideration of the above circumstances. An object of the present invention is to set a detection sensitivity of an impact detection circuit in consideration of a resonance point of an apparatus so that a head is impacted by an impact during a write operation. Provided are a shock detecting circuit for a data recording / reproducing apparatus capable of preventing erroneous writing by moving to an outer track, a data recording / reproducing apparatus having the shock detecting circuit, and a sensitivity setting method of a filter applied to the shock detecting circuit. Especially.

[0013]

A shock detecting circuit for a data recording / reproducing apparatus according to the present invention detects a shock applied to the data recording / reproducing apparatus and outputs a signal according to the strength of the shock, and a shock sensor for detecting the shock. The amplifier that amplifies the output signal from the shock sensor and the high-frequency component of the output of this amplifier are configured to be cut, and the sensitivity at the frequency near the resonance point of the device is set higher than the sensitivity in other frequency regions. And a binarization circuit that binarizes the output of the filter at a constant level, and the output of the binarization circuit is used as a write operation inhibition signal by the head. .

Further, the data recording / reproducing apparatus of the present invention comprises a shock detecting circuit for the data recording / reproducing apparatus having the above-mentioned configuration, and means for prohibiting the write operation by the head according to the output level of the shock detecting circuit. Is characterized by.

Further, in the data recording / reproducing apparatus of the present invention, in addition to the shock detecting circuit, state holding means for holding the output level of the shock detecting circuit, and the head according to the state of the state holding means. A means for prohibiting the write operation, a means for detecting the position of the head from the data of the servo area recorded on the disk read by the head, and a servo data after the write operation is prohibited by the write operation prohibiting means. By continuously checking the state in which the position of the head is not more than the predetermined distance from the target by the positioning control based on the predetermined number of servo data, the holding state of the state holding means is reversed to set the write prohibition state. And a means for releasing.

Further, the sensitivity setting method of the filter applied to the shock detecting circuit for the data recording / reproducing apparatus of the present invention performs the operation of applying vibration of a certain intensity to the data recording / reproducing apparatus while changing the frequency of the vibration. The head misalignment amount is measured each time, and the sensitivity of the filter is set so that the ratio of the misalignment amount to the reference misalignment amount is proportional to the gain of the filter. Characterize.

In the shock detecting circuit for the data recording / reproducing apparatus of the present invention, the gain (detection sensitivity) of the filter in the shock detecting circuit is set in consideration of the resonance point of the data recording / reproducing apparatus, so-called mechanical resonance point. Since the sensitivity at the frequency near the resonance point that moves the head even with a small impact is higher than the sensitivity in other frequency regions,
It becomes possible to detect a small impact having a frequency near the resonance point, which has not been conventionally detected. Therefore, by incorporating such an impact detection circuit in the data recording / reproducing apparatus, it is possible to prevent the head from moving to a track other than the target and being erroneously written due to an impact during the write operation.

Further, the data recording / reproducing apparatus of the present invention incorporating such a shock detecting circuit is provided with a state holding means such as a flip-flop for holding the output level of the shock detecting circuit. The write operation by the head is prohibited according to the state of the means. In this case, unless the state of the state holding means is returned to the original state, the state in which the writing is prohibited continues for a long time even if the change in the head position due to the impact is cured.

Therefore, in the data recording / reproducing apparatus of the present invention, in the positioning control based on the servo data after the write operation is prohibited, the head position is not separated from the target by a predetermined distance or more (that is, the target is predetermined. (A state of being within the distance) is continuously confirmed for a predetermined number of servo data, it is judged that the fluctuation of the head position due to the impact is suppressed, and the holding state of the state holding means is reversed. As a result, the write prohibited state is released. That is, in the data recording / reproducing apparatus of the present invention, after the head is moved due to the impact and the fluctuation of the head position is stopped, it is confirmed that the head can be stably returned to the original position, and the write prohibition is performed. It is possible to prevent the write prohibition state from continuing forever because the state is released.

Further, in the method of setting the sensitivity of the filter applied to the shock detecting circuit for the data recording / reproducing apparatus, the frequency characteristic (frequency dependency) of the displacement of the head with respect to the shock.
Is obtained, and the sensitivity of the filter is set so that the position shift ratio at each frequency and the gain of the filter are proportional, so that the sensitivity at the frequency near the resonance point of the device is set to the sensitivity in other frequency regions. It can be set higher. This makes it possible to reliably detect a small frequency impact near the resonance point, which has not been detected conventionally.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to one embodiment of the present invention.

In FIG. 1, 11 is a disk which is a medium for recording data, and 12 is a head used for writing data to the disk 11 (data recording) and reading data from the disk 11 (data reproduction). The head 12 is provided corresponding to each data surface of the disk 11.

A large number of concentric tracks are formed on both sides of the disk 11, and each track has a plurality of servo areas in which servo data used for positioning control is recorded, as shown in FIG. 2B. 111 are arranged at equal intervals. These servo areas 111 are radially arranged on the disk 11 from the center across each track. A user area 112 is formed between the servo areas 111. Then, one servo area 111 and the following 1
One user area 112 and one servo sector are configured. A plurality of data sectors are set in the user area 112 of each servo sector.

In the servo area 111, an AGC stabilizing area (amplitude AGC area) 111a in which data of a constant frequency is recorded to stabilize the signal amplitude, and sector data indicating erase and sector number (servo sector number) are recorded. The sector data area 111b, the cylinder data area 111c in which the cylinder data indicating the cylinder number (cylinder address) is recorded, and the position information (the position error in the cylinder indicated by the cylinder data) are indicated by the waveform amplitude. It has a well-known area such as a burst area 111d in which a burst signal (burst data) is recorded. The burst signal has two position error signals A and B having different phases and recorded at a position shifted by a half track with reference to the track center.

The disk 11 is a spindle motor (SP
M) 13 to rotate at high speed. The head 12 is attached to a head moving mechanism called a carriage 14 and moves in the radial direction of the disk 11 by the movement of the carriage 14. The carriage 14 has a voice coil motor (V
CM) 15.

SPM (spindle motor) 13 and VC
M (voice coil motor) 15 is a motor driver IC
It is connected to 16. This motor driver IC16
Is an SPM driver (spindle motor driver) 161 for supplying a control current to the SPM 13 to drive the motor 13 and a VCM driver (voice coil motor driver) for supplying a control current to the VCM 15 to drive the motor 15. 162. The value (control amount) of this control current is calculated by the CPU (microprocessor) 20.
Is determined by the calculation process of and is given as an analog value.

Each head 12 is connected to a head IC 17 mounted on, for example, a flexible printed wiring board (FPC). The head IC 17 has a head amplifier 171 that amplifies the analog output read by the head 12.

The head IC 17 is a read / write IC 18
Is connected to The read / write IC 18 inputs the analog output (read signal of the head 12) amplified by the head amplifier 171 in the head IC 17, and performs signal processing necessary for data reproducing operation, for example, analog output to N
Signal processing for conversion into RZ data is performed. The read / write IC 18 also performs signal processing necessary for data recording operation, for example, data that modulates the NRZ data (write data) sent from the disk controller (HDC) 21 and writes it to the disk 11 (for example, 2-7, 1). -7
Signal processing for conversion into modulated data) is also performed.

The read / write IC 18 also executes the above-described normal user data recording / reproducing processing and the servo data reproducing processing necessary for servo processing such as head positioning control.

As shown in FIG. 3, the read / write IC 18 has an AGC amplifier 181, which has an AGC (Automatic Gain Control) function, a pulse generation circuit 182, and a peak hold circuit 183. Pulse generation circuit 182
Is a pulse peak detector (P) for discriminating read data and sync pulse from the read signal from the head 12.
PD) and outputs a data pulse containing cylinder data. The peak hold circuit 183 samples and holds the peak of the read signal from the head 12 and outputs an analog signal including a burst signal.

The read / write IC 19 is connected to a servo processing circuit 19 which executes signal processing required for servo processing. This servo processing circuit 19 is a read / write I
It has a decoding function of extracting and decoding cylinder data (cylinder number) and the like from (the servo data included in) the data pulse from C18, and a timing generation function of a write gate and the like.

The servo processing circuit 19, as shown in FIG.
A decoder 191 for extracting / decoding servo data (cylinder data forming the same) from a data pulse output from the read / write IC 18, and a register (shift register) 192 for holding the extracted cylinder data etc.
And

The CPU 20 is, for example, a one-chip microprocessor. The CPU 20 constitutes a servo processing system (head positioning control mechanism) for executing head positioning control together with the servo processing circuit 19.
The cylinder data extracted by the servo processing circuit 19 is read from the servo processing circuit 19 to read / write IC.
The peak hold signal of the burst signal is read from 18 and the current position is calculated. In addition to head positioning control, the CPU 20 also controls read / write data transfer by controlling the HDC 26.

The CPU 20 is an A / D converter (ADC) 20 for converting the peak hold signal of the burst signal read from the read / write IC 18 into a digital signal.
1 and a D / A converter (DAC) 2 for converting the control amount obtained by the servo processing (data representing the value of the current to be passed through the motors 13 and 15 by the motor driver IC 16) into analog data and outputting it to the motor driver IC 16.
02.

A non-volatile memory such as a ROM 21 is connected to the CPU 20. This ROM21 has C
The control program of PU20 is stored. The disk controller (HDC) 22 is a host device (not shown)
And a magnetic disk device, and mainly transfers read / write data. The disk controller 22 temporarily stores data (data read from the disk 11 and data to be written to the disk 11) transferred between the host device and the magnetic disk device by the disk controller 22. A buffer RAM 23 for connection is connected.

The shock detection circuit 24 detects a shock applied to the device and is connected to the servo processing circuit 19, for example. The impact detection circuit 24 is, for example, the head I.
C17, read / write IC 18, servo processing circuit 1
9, the CPU 20, the ROM 21, the HDC 22, and the buffer RAM 23 are mounted on the same printed wiring board (PCB).

The impact detection circuit 24, as shown in FIG.
A shock sensor 241 that detects a shock applied to the device and outputs a signal proportional to the strength of the shock, and an amplifier 242 that amplifies an output signal from the shock sensor 241.
And a filter 243 for cutting high frequency components of the output of the amplifier 242, and a comparator 244 as a binarization circuit for binarizing the filter output at a constant level (detection level) Vth. . The output of the comparator 244 is supplied to the servo processing circuit 19 as a signal FAULT1 for designating the prohibition of the write operation.

Now, the filter 24 in the impact detection circuit 24
3 is preset so that the sensitivity (gain) at the frequency near the resonance point of the device (mechanism) is higher than the sensitivity in other frequency regions, and at this point, the filter (low-pass filter) in the conventional shock detection circuit is Filter). The sensitivity setting of the filter 243 will be described below.

First, in the present embodiment, at a manufacturing stage of the data recording / reproducing apparatus having the configuration of FIG. 1, a certain strength is provided on the base of the apparatus (here, the mechanical portion including the VCM 15 supporting the head 12). The operation of applying vibration (for example, 0.5 G) is performed by changing the frequency and direction of the vibration (here, X,
By performing the measurement while changing the Y and Z directions) and measuring the positional deviation amount of the head 12 each time, the frequency dependence (frequency) of the positional deviation amount (head moving distance) of the head 12 as shown in FIG. Property).

In the example of FIG. 5, the positional deviation of the head 12 becomes the largest in the vicinity of 0.8 KHz for the impact having the same strength. However, conventionally, the frequency dependency of the positional deviation of the head 12 is not taken into consideration, and the sensitivity (gain) of the filter 243 is set as shown by the broken line in FIG. For this reason, conventionally, when the strength of the shock applied to the device is small, even a shock having a frequency near the resonance point (0.8 KHz in the example of the figure) that causes a large displacement is not detected.

On the other hand, in the present embodiment, the reference positional deviation amount of the positional deviation amount for each frequency obtained from the acquired frequency characteristic as shown in FIG. 5 (for example, the position in the region independent of the frequency) is used. (Shift amount) and the gain of the filter 243 are proportional to each other.
The sensitivity of 3 is set. This filter 24
An example of sensitivity setting of No. 3 is shown by a solid line in FIG. 6 in the case of the frequency characteristic of FIG. As is clear from FIG. 6, the gain of the filter 243 is highest near 0.8 KHz, which is the frequency (resonance frequency) at the resonance point of the device. Therefore, an impact at a frequency near the resonance point of the device that causes a large displacement can be reliably detected even if the intensity is smaller than the impact in other frequency regions.

Next, the operation of the magnetic disk device having the structure shown in FIG. 1 in which the shock detection circuit 24 including the filter 243 whose sensitivity is set as shown in FIG. 6 is mounted will be described. First, when the magnetic disk device configured as shown in FIG. 1 is powered on, the CPU 20 executes various initialization processes.

Next, the CPU 20 is a motor driver IC
The 16 SPM driver 161 is controlled to start the SPM 13, and the rotational movement of the disk 11 is started. Then C
The PU 20 executes an initial seek operation. In this initial seek operation, the CPU 20 controls the V of the motor driver IC 16
By controlling the CM driver 162, servo processing is performed to position the head 12 at the reference position on the disk 11, for example, the cylinder 0.

When an access request is issued from the host device, the CPU 20 performs positioning control for moving the head 12 onto the target cylinder corresponding to the logical address to be accessed, and executes the read / write operation. That is, the CPU 20 executes the speed control to move the head 12 to the target cylinder, and further continuously executes the position control to position the head 12 at the track center of the target cylinder.

Details of the speed control and the position control are as follows. First, speed control will be described. The analog output read from the disk 11 by the head 12 is the head I
The signal is amplified by C17 and supplied to the read / write IC 18, and is separated into two signals in the read / write IC 18 as described below.

That is, in the read / write IC 18, the analog output (read signal from the head 12) amplified by the head IC 17 and further amplified by the AGC amplifier 181.
From the above, the data pulse including the cylinder data is extracted by the pulse peak detection of the pulse peak detector of the pulse generation circuit 182. Further, the peak hold circuit 183 holds (peak-holds) the amplitude of the burst signal (position error signals A and B forming the position information) included in the analog output, and extracts the amplitude from the analog output.

The decoder 191 of the servo processing circuit 19 is
The data pulse extracted by the pulse generation circuit 182 in the read / write IC 18 is input and the cylinder data and sector data in the servo data are extracted and decoded. Cylinder data and the like in the servo data decoded by the decoder 191 are serially input to the register 192 and held in the same register.

The CPU 20 reads the cylinder data and the like held in the register 192 from the servo processing circuit 19 and determines whether or not the head 12 is currently on the correct cylinder.

Further, during speed control, the CPU 20 reads cylinder data (hereinafter referred to as CDx) at the previous sector (servo sector) position and cylinder data read from the current sector (hereinafter referred to as CDy). (Expressed), the moving speed V of the head 12 is calculated by the following equation V = (CDx-CDy) / sector time. Here, the sector time is the time required to rotate (rotate) the disk 11 for one sector.

Further, the CPU 20 calculates the moving distance from the current position obtained from the cylinder data obtained from the servo processing circuit 19 to the target cylinder, and determines the target speed of the head 12 from the moving distance. This target speed is determined by referring to a target speed table prepared in advance in the ROM 21, for example.

The CPU 20 determines the amount of current flowing through the VCM 15 by taking the difference between the moving speed V and the target speed. Then, the CPU 20 converts the determined current amount (digital control amount) into an analog control amount (analog voltage) by the DAC (D / A converter) 202, and the motor driver IC 16
Give to. The VCM driver 162 in the motor driver IC 16 converts the analog voltage supplied from the CPU 20 (through the DAC 202) into a corresponding current (control current) and supplies it to the VCM 15. When a current flows through the VCM 15, a force proportional to the amount of the current is generated, and the carriage 14
Moves.

In this way, the CPU 20 moves the head 12 onto the target cylinder by executing feedback control for driving and controlling the VCM 15 so that the error between the target speed and the moving speed V becomes zero.

Next, the position control operation will be described. First, the CPU 20 obtains cylinder data from the servo processing circuit 19 as described above, and also reads / writes the IC 18
The peak hold signal of the amplitude of the burst signal (the position error signals A and B forming the burst signal) extracted by the peak hold circuit 183 therein is obtained through the ADC (A / D converter) 201. That is, the CPU 20 performs A / D (analog / digital) conversion on the amplitude of the burst signal (which constitutes the position error signals A and B) peak-held by the peak-hold circuit 183 in the read / write IC 18 in addition to the cylinder data. Data (Digital burst data BS
TA, BSTB).

The CPU 20 determines the position error (position on the track) BSTREF of the target cylinder of the head 12 based on the obtained burst data (BSTA, BSTB).
Is expressed by the following equation BSTREF = (BSTA−BSTB) / (BSTA +
BSTB). Here, BSTA-BSTB represents the amount of deviation of the head 12 from the track center.

The CPU 20 then calculates the position error B
Digital filter arithmetic processing for phase compensation for STREF is executed. Specifically, the CPU 20
Is the calculated position error BSTREF and BSTREF and 1 before 1 to N samples, for example, 1 to 3 samples before.
Up to 3 samples before, using the output value (control amount), B
Digital filter arithmetic processing for performing phase compensation for STREF is performed by the following equation: y (i) = [b (i) x (i) + b (i + 1) x (i +
1) + b (i + 2) x (i + 2) + b (i + 3) x (i
+3)]-[a (i + 1) y (i + 1) + a (i + 2)
y (i + 2) + a (i + 3) y (i + 3)]. Where y (i) is the output value before i samples, x (i) is the position error BSTREF before i samples,
a (i) and b (i) are parameter values of the digital filter.

Next, the CPU 20 determines the calculated position error BS
The control amount (digital control amount) obtained by TREF and the filter calculation process is determined, and converted into an analog control amount (analog voltage) by the DAC 202 and then the motor driver I
By giving it to C16, the VCM driver 162 is controlled. The VCM driver 162 converts the analog voltage given from the CPU 20 into a corresponding current (control current) and supplies it to the VCM 15.

In this way, the CPU 20 controls the head 12
So that the position error with respect to the track center of
The head 12 is positioned at the track center of the target cylinder by executing feedback control for driving and controlling the VCM 15.

When the positioning control of the head 12 including the above speed control and position control is completed, the read / write operation is executed as follows. First, in the case of a read operation, the HDC 22 sets a read gate (signal) for giving a timing of data read from the disk 11. Then, the head 12 reads the recording information of the designated sector of the target cylinder.

The read / write IC 18 reproduces read data from the read signal (recording information of the designated sector of the target cylinder) read by the head 12, and the HDC 22
To (serial transfer). The HDC 22 temporarily stores the read data in sector units in the buffer RAM 23, and transfers the read data for the sector corresponding to the logical address to be accessed to the host device.

On the other hand, in the write operation, the HDC 22 first writes the write data transferred from the host device into the buffer RA.
It is temporarily stored in M23. If a fault (signal) FAULT2, which will be described later, is not true, the HDC 22 sets a write gate (signal) WG1 for giving a data write timing to the disk 11, and sequentially reads / writes the write data in sector units IC18. Transfer to. The read / write IC 18 has a write gate (signal) W
While the write gate (signal) WG2 corresponding to G1 is set, the write data transferred from the HDC 22 is converted into a write current and supplied to the head 12 via the head IC 17. The head 12 converts the write current into a recording magnetic field, and the user area 1 of the designated sector of the target cylinder.
12 (see FIG. 2A).

However, during such a write operation,
It is assumed that the head 12 is moved to the adjacent track due to the impact applied to the device. When a shock is applied to the device, the shock sensor 241 in the shock detection circuit 24 outputs a signal proportional to the strength of the shock. This shock sensor 241
The output signal from the filter 242 is amplified by the amplifier 242 and is output to the filter 2
Guided to 43. The gain characteristic (frequency-gain characteristic) of the filter 243 is set in advance so that the gain (sensitivity) becomes high at a frequency near the resonance point of the device, as shown in FIG. Therefore, when a shock having a frequency near the resonance point is applied, even a small shock can be detected with certainty.

The output of the filter 243 is the comparator 24.
4 is supplied. The comparator 244 uses the filter 24
3 output levels and preset (as threshold)
The detection levels Vth are compared with each other, and the output level of the filter 243 is true (for example, logic "1") only during a period in which it is larger.
Output a value signal. This binary signal is a fault (signal)
When the fault (signal) FAULT1 is true, it indicates that the head 12 has detected an impact that deviates from a certain range based on the track center of the target cylinder.

The fault (signal) FAULT1 output from the comparator 244 is supplied to the servo processing circuit 19. As shown in FIG. 7, the servo processing circuit 19 is provided with a flip-flop (F / F) 193 set by a power supply abnormality detection by a known means, and a fault (signal) FAULT1 (becomes true). A flip-flop (F / F) 194 that is set and a flip-flop (F / F) 195 that is set when the CPU 20 detects a servo error are provided.
Further, the servo processing circuit 19 receives the write gate (signal) WG1 from the HDC 22 according to the Q output (of logic "1") of the F / Fs 193 to 195.
2 and AND gate 196 for outputting to the head IC 17 and the read / write IC 18, and F / Fs 193 to 195.
An OR gate 197 for ORing each Q output (indicating that the Q output is an inverted output of the Q output) of the above and outputting it as a fault FAULT2.

Now, the fault (signal) FAULT supplied from the comparator 244 (in the shock detection circuit 24)
When 1 becomes true, F / F 194 sets. F / F1
When 94 is set, the AND gate 196 is closed and the write gate WG2 becomes false. As a result, the write operation is prohibited, and it is possible to prevent the head 12 from moving and writing to the adjacent track due to the impact applied to the device.

When the F / F 194 is set, the OR gate 197 sets the fault FAULT2 to true, and the CP
Notify U20 and HDC 22 of the fault condition. Now, the CPU 20 causes the above-mentioned BSTREF = (BSTA−BSTB) / (BSTA +
BSTB) is sequentially calculated, and V is calculated based on the calculation result so that the position error of the head 12 with respect to the track center becomes zero.
Feedback control (position control) for driving and controlling the CM 15 is always executed.

Therefore, when the head 12 is moved to, for example, an adjacent track due to a shock applied to the device, the CPU 20 can know the state from the above calculation result. Therefore, when the CPU 20 determines from the above calculation result that the position of the head 12 has moved outside the predetermined range, it outputs an error signal and outputs the F / F 19
Set 5. The determination process of the CPU 20 is a ROM
Since it is performed according to the control program stored in No. 21, it cannot be performed at high speed as described in the section of "Prior Art". Therefore, the fault FA from the impact detection circuit 24
The F / F 195 will be set later than the time when the F / F 194 is set by the ULT 1.

The CPU 20 receives the fault status (fault FAULT) from the OR gate 197 in the servo processing circuit 19.
Even after 2) is notified, the servo data extracted by the servo processing circuit 19 is fetched, and the position control of the head 12 is continued based on the servo data. As a result, when the positional fluctuation of the head 12 due to the impact is stopped, the moved head 12 returns to the track center of the target cylinder by the position control of the CPU 20.

Therefore, based on the above calculation results, the CPU 20 determines that the head 12 has returned within a predetermined range, that is, that the head 12 is not separated from the target position by a predetermined distance or more. (Number of times servo data was captured) If you check it continuously, the head 1
It is judged that the position fluctuation of No. 2 has subsided and the head 12 has been stably positioned at the track center of the target cylinder, and F / F193 to F / F195 (or F / F19
4, 195) to reset the write operation prohibition state. Then, the CPU 20 restarts the write operation for the HDC 22. As a result, it is possible to prevent a problem that the state in which the writing is prohibited continues for a long time despite the head position fluctuations being subsided.

Although the magnetic disk device has been described in the above embodiments, the present invention seeks a head at a specified position on the disk based on servo data recorded on the disk, such as a magneto-optical disk device. The present invention is generally applicable to data recording / reproducing devices that control positioning.

[0070]

As described in detail above, according to the present invention, by setting the detection sensitivity of the shock detecting circuit in consideration of the resonance point of the device, the strength of the shock applied to the device is reduced. However, if the frequency of the impact is near the resonance point (a small impact causes a large head movement), the impact can be reliably detected, and the head is not intended due to the impact during the write operation. It is possible to prevent accidental writing by moving to another track.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic disk drive according to an embodiment of the present invention.

FIG. 2 is a diagram showing a disk format applied in the embodiment.

3 is a block diagram showing a main configuration of a read / write IC 18 and a servo processing circuit 19 in FIG.

FIG. 4 is a block diagram showing a configuration of a shock detection circuit 24 in FIG.

FIG. 5 is a diagram showing a measurement example of a head movement distance with respect to a shock frequency (vibration frequency) when a constant strength shock is applied to the apparatus.

FIG. 6 is a view showing an example of sensitivity setting of a filter 243 in FIG.

7 is a diagram showing the configuration of a write gate control mechanism included in the servo processing circuit 19 in FIG.

FIG. 8 is a diagram showing a general relationship between a head and a track layout (arrangement).

[Explanation of symbols]

11 ... Disk, 12 ... Head, 13 ... SPM (spindle motor), 14 ... Carriage, 15 ... VCM (voice coil motor), 17 ... Head IC, 18 ... Read / write IC, 19 ... Servo processing circuit, 20 ... CPU (Write prohibition state releasing means), 21 ... ROM, 22 ... HDC, 24 ... Impact detection circuit, 111 ... Servo region, 193 to 194 ... F / F (flip-flop, state holding means), 196 ... And gate (write operation) Prohibition means), 197 ... OR gate, 241 ... Shock sensor, 242 ... Amplifier, 243 ... Filter, 244 ... Comparator (binarization circuit).

Claims (4)

[Claims] 1. A shock detecting circuit for a data recording / reproducing apparatus, which is applied to a data recording / reproducing apparatus for performing differential recording / reproduction of data by a head, detecting a shock and outputting a signal according to the strength of the shock. Shock sensor, an amplifier that amplifies the output signal from this shock sensor, and a high-frequency component of the output of this amplifier that is configured to be cut, and the sensitivity at frequencies near the resonance point of the device A filter which is set higher than the sensitivity in the region and a binarization circuit which binarizes the output of the filter at a constant level are provided, and the output of the binarization circuit is used as a write operation inhibition signal by the head. A shock detection circuit for a data recording / reproducing apparatus, which is characterized by being used. 2. A data recording / reproducing apparatus for positioning and controlling a head for recording / reproducing data on the basis of servo data recorded on a disc at a designated position on the disc, detecting impact, and detecting the intensity of the impact. A shock sensor that outputs a signal in accordance with the above, an amplifier that amplifies the output signal from this shock sensor, is configured to cut the high frequency component of the output of this amplifier, and has sensitivity at a frequency near the resonance point of the device. Is set higher than the sensitivity in other frequency regions, and a shock detection circuit having a binarization circuit that binarizes the output of this filter at a constant level, and according to the output of this shock detection circuit, A data recording / reproducing apparatus comprising: means for prohibiting a write operation by the head. 3. A data recording / reproducing apparatus for positioning and controlling a head for recording / reproducing data on the basis of servo data recorded on a disc at a designated position on the disc, detects impact, and detects the intensity of the impact. A shock sensor that outputs a signal corresponding to the shock sensor, an amplifier that amplifies the shock sensor output, and a high frequency component of the output of this amplifier are configured to be cut, and the sensitivity at frequencies near the resonance point of the device A shock detection circuit having a filter set higher than the sensitivity in the frequency domain and a binarization circuit that binarizes the output of this filter at a constant level, and a state for holding the output level of this shock detection circuit Holding means, means for prohibiting write operation by the head according to the state of the state holding means, and reading by the head Means for detecting the position of the head from the data of the servo area recorded on the disk, and after the write operation is prohibited by the write operation prohibiting means, the position of the head is targeted by the positioning control based on the servo data. A state in which the state is not separated by a predetermined distance or more for a predetermined number of servo data continuously, and means for reversing the holding state of the state holding means and canceling the write prohibition state. Data recording / reproducing device. 4. A shock sensor, which is applied to a data recording / reproducing apparatus for recording / reproducing data by a head, detects a shock, and outputs a signal according to the strength of the shock.
An amplifier for amplifying the output signal from this shock sensor, a filter for cutting high frequency components of the output of this amplifier, and an output of this filter at a constant level
A method for setting the sensitivity of a filter applied to a shock detecting circuit for a data recording / reproducing device, comprising: a binarizing circuit for binarizing, wherein an operation of applying a vibration of a certain intensity to the data recording / reproducing device is performed. Is performed while changing the frequency of the head, and the position displacement amount of the head is measured each time, so that the ratio of the position displacement amount to the reference position displacement amount and the gain of the filter are proportional. A sensitivity setting method of a filter applied to a shock detection circuit for a data recording / reproducing device, characterized in that sensitivity setting is performed,